sched/psi: Fix OOB write when writing 0 bytes to PSI files

[sfrench/cifs-2.6.git] / kernel / sched / psi.c

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index db7b50bba3f1f181e03e5911f365759ecf3acf99..38ccd49b9bf6c59fdc9c6f537df97ae94ac23fed 100644 (file)
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -1199,6 +1199,9 @@ static ssize_t psi_write(struct file *file, const char __user *user_buf,
        if (static_branch_likely(&psi_disabled))
                return -EOPNOTSUPP;
 
+       if (!nbytes)
+               return -EINVAL;
+
        buf_size = min(nbytes, sizeof(buf));
        if (copy_from_user(buf, user_buf, buf_size))
                return -EFAULT;